1. Field
Embodiments of the present invention relate to an adhesive composition for polarizing plates, a polarizing plate using the adhesive composition, and an optical display including the polarizing plate.
2. Description of the Related Art
An adhesive is often used in polarizing plates to bond a protective film to one or both surfaces of a polarizer that includes a PVA film. However, when the adhesive is a hydrophilic and water-soluble water-based PVA adhesive, the heat from a backlight unit may change the dimensions of the polarizing plate, resulting in a distortion due to such dimensional change that is localized in a portion of a screen. Accordingly, when a black color is displayed on the screen, significant light leakage can occur (e.g. a rainbow stain may appear, which indicates a partial light leakage).
When the adhesive is a cationic polymerizable UV curable adhesive, a “dark reaction” (post-polymerization) may occur after UV irradiation stops and the cured product is wound into a roll for storage. In addition, cationic polymerizable UV curable adhesives are easily affected by humidity upon curing and are likely to suffer from deviations of the curing state. Thus, to realize a uniform curing state, strict controls must be placed on environmental humidity and the moisture content of the PVA polarizer.
In recent years, polarizing plates have been used in extreme and severe environments, giving rise to an increased demand for polarizing plates exhibiting reliable moisture resistance under severe moisture environments, such as high humidity environments, water immersion environments and the like.